LAUSR

Undoped and Bi2O3-doped glasses from the system Na2O–CdO–P2O5 were prepared and studied through investigating their optical and FTIR spectra before and after gamma irradiation beside measuring their thermal expansion properties. Optical spectra reveal distinct UV absorption with additional peaks upon introducing Bi2O3 added with different concentrations from 1 to 7.5%. The UV absorption of the undoped sample is related to trace iron impurities while the extended UV absorption peaks are correlated with absorption of Bi3+ ions. FTIR spectra show condensed phosphate groups (Q2, Q3 units) beside the sharing of bismuth ions in their vibrational sites. Gamma irradiation causes limited changes in the UV spectra but involves the generation of an induced visible band in the undoped glass. These changes are assumed to be due to some suggested photochemical reactions on the trace iron impurities and the formation of an induced visible (POHC) band on the phosphate network. Careful inspection of the selected deconvoluted spectra for the undoped glass and doped (7.5 wt%) supports the introduced assumptions. The thermal expansion parameters are correlated with the type of bonding of bismuth ions within the network structure.